Dive into a forum discussion about a new PC game, and one word will inevitably show up: optimization. Deus Ex: Mankind Divided? "I think this game is not optimized AT ALL!" writes one player on Steam. Metro: Last Light? "In a few words optimization in this game is terrible," writes another.

Complaints about bad optimization are often shorthand for 'this game doesn’t run well on my PC.' But is that performance really the fault of the game’s programming not being written as efficiently as possible? How do you really know if a game is poorly optimized, or simply pushing your PC to its limits?

This article will try to clarify what optimization actually is, give an overview of some technical features like lighting and anti-aliasing that are inherently computationally expensive, and shed some light on how developers actually determine graphics presets and system requirements. Thanks to Croteam and QLOC for providing invaluable insight into the process of optimization.

To make it more digestible, this article has been split up into the three pages. Page two features the densest technical discussion, so jump to page three if you mostly want to know about how optimization is carried out.

What is optimization, and can we measure it?

Optimization in gaming discussions doesn’t mean the same thing it means in computer science. Rather than referring to making a process optimal, it generally means making things better. The crucial difference is that in computer science, optimization is only considered as such if it produces the exact same outcome.

As a very simple example, if you wanted to calculate:

a = b*c + b*c + b*c

Instead, calculating:

d = b*c, and setting a = d + d + d

would be an ‘optimization’—it only requires one multiplication rather than three for the same result. By this strict definition, the idea of comparing the level of optimization across distinct games trying to accomplish different things becomes completely impractical.

More on graphics settings

So how do we talk about game optimization while maintaining some level of objectivity? Here’s the definition QLOC gave me:

"Good optimization means that the game works at the same framerate across a wide range of hardware specs, including low-end configurations."

Maintaining that reliable framerate is where they see the importance of graphical settings, since they can bridge the large technological gap between low- and high-end PCs.

Croteam’s Dean Sekulic, who has been optimizing games for more than 20 years, believes that "on the one hand, no, you cannot compare whether different games are optimized or not", but that it should be possible to form a judgement by looking at the quality of the output produced by two different games and the relative performance they achieve. However, he cautions that "there are also lots of things under the surface" that influence how a game may perform.

What kinds of things? Understanding optimization, and what affects it, means answering that question. We’ll start with judging the performance impact of graphical effects that are especially demanding on current hardware.